Winding mandrel for packaging glass strands



June 23, 1959 x R. E. SMITH 2,891,798

-, W 3 f v E ATTUHN Y5 June 23, 1959 v R. E SMITH 2,891,798

WINDING MANDRELFOR PACKAGING GLASS STRANDS I Filed Nov. 13, 1956 2Sheets-Sheet z INVENTOR;

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United States Patent WINDING MANDREL FOR PACKAGIN GLASS STRANDS Roy E.Smith, Anderson, S.C., assignor to Owens-Coming Fiberglas Corporation, acorporation of Delaware Application November 13, 1956, Serial No.621,785

5 Claims. (Cl. 279-2) The present invention relates generally tomechanism for drawing and winding a glass thread or strand of the typeformed by gathering together a large number of attenuated glassfilaments. More specifically the invention pertains to a mandrel forholding an expansible, resilient tube upon which a glass strand is woundinto a package.

Because of the inherent greater strength of a glass strand and the speedwith which it has been customarily wound upon spools or tubes, a greatercompression force is developed in the winding operation than accompaniesthat of other fibers of natural and synthetic origin.

This high compression force has the objectionable elfect of constrictingthe commonly used plastic forming tube, preferred because of its lightweight and wearing qualities, into a smaller diameter, which makes itdifficult to remove the tube from the mandrel. It also is inclined tobind the turns of the glass strand so tightly together around the tubethat the unwinding operation for subsequent use or treatment, such astwisting and plying, is jerky and uneven.

During the first production of glass strands these difiiculties wereencountered and in efforts to overcome them special mandrels for holdingthe winding tubes were developed. A typical design and one successfullyused in modified form for many years is shown in US. Patent No.2,274,681 granted to Fletcher on March 3, 1942. In this device andvariations thereof, there are long narrow fingers, loosely carried bythe mandrel, which are thrust outwardly against the interior surface ofthe forming tube by the centrifugal force developed by the rotation ofthe mandrel in the winding process. This centrifugal force neutralizedthe constricting effect of the strand winding upon the tube, leaving thetube loose enough upon the mandrel to be easily removed. Also thecentrifugal force slightly expanded the tube during rotation of themandrel; and the return of the tube to its original size at thetermination of the rotation sufficiently reduced the binding betweenturns of the thread that subsequent unwinding of the thread or strandfrom the tube was smoothly accomplished.

While mandrels of a design typified by the showing of the Fletcherpatent served quite efficiently for many years, recently, under the moredemanding requirements arising in an expanding industry, theirperformance has proved inadequate.

Constantly growing uses and sales have called for ever increasingproduction. This demand was satisfied through the adoption of improvedglass compositions, and glass melting and feeding equipment, developedby vigorous research, which made it feasible to draw and wind glassfilaments into strands at considerably greater speeds. Winding tubes arenow frequently rotated at or in excess of ten thousand revolutions perminute. The compression force upon the tube developed by the windingoperation has increased accordingly and to a degree that the Fletchertype mandrels have difficulty in withstanding. Failure has beenencountered most frequently when an elongated mandrel and tube wereutilized for receiving two separate strands to form two packages ofwound strands on the single tube.

Investigation by applicant has led him to conclude that the fingers ofthe established mandrel design possessed insutficient mass to create thecorrect centrifugal force to properly counteract the constricting forceof the winding operation, and that the comparatively thin fingerretaining structure of the mandrel likely deformed or bulged outwardlyunder higher speeds and in their elongated form required for doublepackages. Then, too, the fingers were spaced quite a distance apart andtheir separated lines of thrust could effect an out-of-round expansionof the tube.

Additionally, applicant observed that the number and arrangement ofparts of the previously used mandrel made the mandrel rather expensiveto build and the parts diflicult to align and assemble. It was alsonoted that the outer section of the wound strand in the final packagewas more inclined to be under too great a tension for easy unwinding.

The principal object of this invention is broadly to provide a windingmandrel that will function efiiciently in supporting an expansible,resilient tube upon which either one or two glass strands are veryrapidly wound and to produce packages of glass strands so formed thatare fully satisfactory in subsequent use.

More specifically, a prime object of this invention is to providecentrifugally propelled elements adapted to embrace the major portion ofthe inner surface of a winding tube mounted on the mandrel.

Another object is the provision of a mandrel which expands the resilientwinding tube in a manner that results in no serious binding between thecourses of the glass strand wound in a package around the tube.

A further object is to provide a mandrel having a minimum number ofparts which can be economically produced and easily assembled.

Other objects and advantages are also secured through the novel featuresof the invention of which the following are considered of specialpertinence.

Instead of spaced narrow fingers for engaging the inner circumference ofthe winding tube, the mandrel of this invention has segments of T crosssection with outer surfaces contacting the major portion of the interiorof a tube mounted on it.

A single piece, solid core constitutes the main body member of a mandrelembodying the invention. The core has an axial bore for receiving adriving spindle and outer grooves acting as retaining sockets for thesegments.

The core and the segments have cross sections of uniform dimensionsthroughout their lengths.

The weight of the segments is proportioned in respect to the developedwinding compression to permit gradual contraction of the expanded tubeduring the last portion of the package formation.

Attention will be directed to other features of the invention in thefollowing description and by reference to I the drawings.

In the drawings,

Figure l is a diagrammatic illustration of a conventional process forglass strand forming and winding into packages;

Figure 2 is a longitudinal section, taken on line 2--2 of Figure 3, of amandrel and tube embodying the invention;

Figure 3 is a partial end view and cross section of the mandrel ofFigure 2, the section being taken on the line 3-3 of Figure 2;

Figure 4 is a perspective view of one of the segments; and

Figure is an enlarged broken section comparable to the section of Figure3 showing the segments depressed during the last part of the windingoperation.

Referring to the drawings in more detail, in Figure l is depicted,diagrammatically, a glass melting furnace 6 and a multiple-nozzlebushing 7 from which streams of glass 8 are discharged and attenuatedinto continuous filaments. The individual filaments, which usuallynumber from one to two hundred, are gathered together into a singlethread or strand 9 by a device such as hook 10.

A sizing coat is generally applied to the filaments adjacent thegathering device by some means such as a spray nozzle or by being passedover a pad saturated with a sizing liquid. The strand 9 is then drawndown and wound into a package 13 upon the spool or tube 12. A traversingdevice as indicated at M guides the strand back and forth over tube 12.The traversing mecha nism 14 is a figurative showing of that disclosedin the patent to Fletcher No. 2,377,771 dated June 5, 1945. Thismechanism may, of course, be of any conventional design capable offunctioning at the high speed required.

A bracket 15 supporting spindle 16 on which the tube mandrel 18 ismounted extends upwardly from the housing (not shown) containing themotor and driving mecha nism for rotating the spindle through belt 19running over pulley 29. More details of spindle it: and mandrel 18 maybe observed in the subsequent figures of the drawing, with attentionfirst directed to Figure 2. As seen in this view a bearing assembly 21,one of a pair Within the bracket 15, supports the spindle close to theposition of the mandrel on the spindle. The core 24, constituting themain body of the mandrel 18, is held on the spindle against the taperedenlargement 26 of the spindle by a lock nut 27.

In the disclosed embodiment, the core 24 has twelve grooves 39 runninglongitudinally in the outer face of the core for the full lengththereof. The grooves are similarly dimensioned and symmetricallypositioned. They are dovetail in cross section, being wider at theirbases.

Above the flat bottom of each groove is a shallow section with straightsides. From this section the sides converge upwardly. The convergingpart 31 of the groove terminates in a narrow straight-sided top portion32.

Locked within each groove and extending the full length thereof is atube contacting segment 34. The segment has a T cross section with aflaring base 35 conforming in contour with the converging part 31 of thegroove. The portion of the segment, forming the top of the T section, isdisposed exteriorly of the core and has an outer surface curved to fitthe inner circumference of the winding tube positioned on the mandrel.The segment has a short straight-sided neck 37 joining the top of thesegment with the flaring base 35.

The ribs 38, lying between the grooves, are slightly peaked. Each flathalf of the peak shape is below the flat underside of one side of the Tportion of the adjacent segment.

The segments 34 are inserted into the grooves from the exposed end ofthe core before the head piece is fastened by bolts 41 upon the outerend of the core. The segments are then retained within the groovesbetween head piece dt? and the collar 43 bolted against the other end ofthe core.

In each groove beneath the base 35 of the segment is a generally fiatspring 46 extending in a slight are between the ends of the groove.These springs incline the segments to their outermost positions whenthere is no tube over the mandrel, as illustrated in Figure 3.

In the use of the mandrel of this invention, the wind ing tube 12 isfirst placed over the mandrel. depress the segments 34 against the lighttension of the springs 46. The outer ends of the segments are tapered tofacilitate depression of the segments by the tube. The

springs have sufficient strength to retain the tube in place withoutimpeding its easy removal. While the tubes are generally conventional inshape and in their plastic composition, for purposes of this inventionit is very desirable that their resilience and dimensions be uniform.

Before the winding drive is actuated to turn the mandrel with the tubemounted on it, the starting end of the glass strand is manually tiedaround the tube. With the glass strand thus secured to the tube theWinding drive is set in operation. This may be accomplished throughrelease of a clutch which has been held in drive-disengaging position bythe foot of the operator while he placed the tube on the mandrel andfastened the leading end of the glass strand around the tube. As thetube acceleretes to its selected speed (which may be ten thousand ormore revolutions per minute) the segments are pro polled by centrifugalforce from their retracted positions upon the springs outwardly againstthe interior of the tube.

The outward movement of the segments is radially guided by slidingcontact between the straight sides of the narrow part 32 of the groovesand the necks 37 of the segments. With the uniform cross sectionthroughout their lengths the segments apply pressure evenly against theinner wall of the tube.

The initial outward thrust of the segments moves them as far as theirloose retention within the grooves permits. This brings the flaring base35 of each segment against the complementarily converging portion 31 ofthe groove, as illustrated in Figure 3. Upon the tube now expanded toits maximum diameter, the glass thread is Wound with the turnsdistributed back and forth across the tube by the action of thetraversing mechanism 14.

With the strength of the current glass compositions and at the new highspeeds of rotation, considerable constricting force upon the tube isdeveloped by the winding operation. The mass of the segments, however,is such that enough counter pressure is exerted to hold the tube in itsfully enlarged form until a substantial portion of the package of giassstrand is wound upon the tube.

As the diameter of the wound package becomes larger the centripetalwinding pressure increases. This is due, not only to the faster drawingof the strand required to supply the longer length to circumscribe thegrowing package during each revolution, but also to the slightstretching of the glass strand as it is wound. While the elasticproperty is limited to a maximum elongation of three percent, it issufficient to produce a build up of the inwardly directed pressure asthe layers of the strand accumulate.

Of those elements contributing to the development of the opposed forces,those subject to control are preselected in order to permit theincreasing centripetal winding pressure to slowly overcome thecentrifugal pressure of the segments during the finishing portion of thepackage forming operation. The mass of the segments is one of the mostgovernable elements and its modification is the principal means ofattaining the desired relationship between the opposed forces.

The sturdy, solid construction of the core resists any deformation dueto centrifugal force and therefore does not adversely influence theshape of the tube. The segments also are built with sufiicient crosssection that they remain fully rigid, and cooperate in applying anexpanding pressure uniformly against substantially the full innersurface of the forming tube. The non-deflecting character of the coreand segments enable them to be utilized in elongated form to receive andproperly wind two strands into separate packages upon a tube of a lengthsuitable for double packaging.

The core and the segments constituting the main parts of the mandrel,and there being no intermediate elements, the mandrel is more easilyproduced and assembled. No alignment problem is involved.

The tapered contact area between the segments and the converging sidesof the grooves, when the segments are in their most expanded positions,is most effective in firmly retaining the segments in place. This designmakes both the core and the segments stronger than they would be withmore severe undercutting to provide fiat contact between these elements.

The tapered surfaces of the grooves not only oppose the outward thrustof the segments but are also adapted to receive lateral pressure fromthe segments when they tend to move tangentially during the periods ofacceleration and deceleration. This reduces the wear from such sidethrust to which the straight radially guiding sides of the groove andthe necks of the segments would otherwise be subjected.

It should be observed that the core and the segments together constitutea substantially solid, symmetrical, cylindrical mass with the exteriorportions of the segments completing the cylinder in which the polyhedralcore is inscribed. There is, accordingly, no area in the assembly whereweight is concentrated which in rotation might cause a whipping ortwisting effect.

While the disclosed embodiment of the invention is a preferred formvarious modifications may be resorted to within the scope of theinvention and without too detrimental effects.

For instance, square instead of angled shoulders may be utilized forretaining the segments Without seriously jeopardizing the advantagesgained through other features of the invention. Also, a mandrel havingwider spacing between tube contacting faces of adjoining segments wouldserve satisfactorily in many cases. The particular number and shape ofthe segments selected for disclosure herein may, of course, bemoderately altered without loss in their overall efiectiveness.

I claim:

1. A rotatable mandrel for holding an expansible, resilient tube uponwhich a glass strand or the like is wound to form a package, whichcomprises as integral, cylindrical body member with an axial bore forreceiving a driving spindle, and segmental elements of T cross sectioncarried by the body member and extending the full length thereof, saidelements being movable by centrifugal force, upon rotation of themandrel, radially and outwardly from the body member, both said bodymember and said segmental elements being solidly formed with asubstantially uniform cross section throughout their lengths, wherebyunder rotation of the mandrel they are not deformed by centrifugal forceand the elements are moved outwardly with equal longitudinallydistributed force.

2. A rotatable mandrel for holding an expansible, resilient tube uponwhich a package of glass strand is wound, including an elongated,generally cylindrical body, substantially solid and uniform in crosssection; gripping members, outwardly movable by centrifugal force,carried by the body and extending the full length thereof, said membersbeing of uniform T shape in cross section; guiding means on the bodycomprising longitudinal grooves therein directing the members in radialpaths, and limiting means comprising shoulders of lateral recesses inthe grooves, restricting the outward centrifugal movement of themembers.

3. A rotatable mandrel for holding an expansible, resilient tube uponwhich a glass strand is wound to form a package, which comprises anintegral body member of generally cylindrical form having an axial borefor reception of a driving spindle and with exterior longitudinalgrooves extending the full length of the body member; elongatedsegmental elements carried by the body member and movable by centrifugalforce radially and outwardly therefrom, inner leg portions of thesegmental elements projecting into the grooves and radially guidedthereby, exterior portions of the segmental elements being laterallybroadened; and elongated springs lyin-g lengthwise in the grooves andarranged to impel the segmental elements outwardly; said body member,segmental elements and springs being of approximately equal length,whereby they all contribute to the uniform distribution of the weightof'the mandrel.

4. A rotatable mandrel for holding an expansible, resilient tube uponwhich a glass strand is wound into a package, which comprises anintegral body member having an axial bore for reception of a drivingspindle and exterior grooves of dovetail cross section extendinglongitudinally of the body member, and segmental elements carried by thebody member and movable by centrifugal force radially and outwardlytherefrom, inner portions of the segmental elements projecting into thegrooves and having lateral enlargements disposed beneath the angledshoulders of the dovetail configuration of the grooves, whereby outwardmovement of each segmental element caused by centrifugal force developedby rotation of the mandrel, is limited by the abutment of the lateralenlargements of the element against the angled shoulders of theassociated groove.

5. A rotatable mandrel for holding an expansible, resilient tube uponwhich a package of a glass strand is wound, which comprises a bodymember having exterior grooves running longitudinally thereof, saidgrooves being roughly dovetail in cross section, broadened at theirbases with sides converging from the bases to upper narrow sections ofthe grooves, said narrow sections being bounded by straight parallelextensions of the sides; segmental elements of T section carried by thebody member and movable upon rotation of the mandrel by centrifugalforce radially and outwardly therefrom, and legs on the segmentalelements, constituting the upright portion of the T section, extendinginto the grooves, said legs having a lower flaring section and an uppergenerally straight portion, the grooves and the legs being so arrangedthat the narrow sections of the grooves guide the segmental elements intheir radial movement by contact with the upper, generally straightportions of the legs, and the converging sides of the grooves limit theoutward movement of the segmental elements by intercepting the lowerflaring sections of the legs.

References Cited in the file of this patent UNITED STATES PATENTS 16,748Reynolds Mar. 3, 1857 1,870,649 Rawson Aug. 9, 1932 2,128,980 AndertonSept. 6, 1938 2,274,681 Fletcher Mar. 3, 1942 2,690,914 Bryant Oct. 5,1954 2,738,980 Spahn Mar. 20, 1956

